Locomotive axle and crank pin and method of constructing the same



Dec. 20, 1932.

C. J- SCUDDER LOCOMOTIVE AXLE AND CRANK PIN AND METHOD OF CONSTRUCTINGTHE SAME Filed Nov. 3. 1931 INVENTOR (harks J .Scydder ATTORNEY PatentedDec. 20, 1932 UNITED STATES PATENT OFFICE CHARLES J. SCUDDER, OFSCRANTON, IENNSYL-VANIA LOCOMOTIVE AXLE AND CRANK PIN AND METHOD OFCONSTRUGTING THE SAME Application filed November 3, 1931.

My invention relates to construction of locomotive axles and crank pinsand a more exact method of obtaining final heat treatments thereof, andhas for its object the provision of construction and method therefor ofthe character designated which shall effectlvely greatlyprolong theservice life of axles and crank plns and greatly increase their initialstrength.

A further object of my invention is to provide locomotive axles andcrank pins which shall comprise an outer surface of ductile, resilientmaterial suitable to resist bearing friction and rolling and chafingaction of the journals, and a center portion of harder, tougher andstronger materials to more effectively resist torsional and bendingstrains.

A still further object of my invention is to provide a compositestructure of the character described comprising an outer shell havingductile wearing properties suitable for exterior fit bearings, and aninterior structure of a tougher, stronger, strain resisting, hardermaterial, the whole having each part separately heat treated andafterward fitted together to form a unitary structure.

A still further object of my invention is to provide by a'method ofconstruction a composite locomotive axle and crank pin whereby toincrease their wearing and enduring qualities and initial strengthswhich shall avoid certain inequalities of grain structure found inforgings of large diameters.

A still'further object of my invention is to provide a method ofconstructing composite locomotive axles and crank pins whereby theseparate parts entering into the composite structure lend themselvesmore readily to more reliable heat treatment than with suchconstructions as heretofore known in the art, whereby the metal enteringinto the construction is more exactly and evenly treated resulting in amore homogeneous undisturbed crystalline structure.

As is well known in the art to which my Serial No. 572,813.

invention relates, locomotive driving axles and crank pins have alwayscaused considerable trouble, due to failure after certain limitedperiods of service. These failures are usually brought about by exteriorfractures or heat checks which work progressively inward and finallywork their way through the entire axle or crank pin journal untilfailure occurs. Such failure with the locomotive in service is a seriousone, sometimes entailing much greater damage than the breakage of the-member itself and danger to the lives of the occupants of thelocomotive and train.

To obviate such failures, it has become the practice of a number ofrailroads to place a definite age limit on axles and crank pins at whichtime they are removed from the locomotives and replaced by new ones,regardless of whether they show any evidence of weakness or failure ornot. Other railroads have established a minimum diameter for these partsso that as soon as they wear down to the minimum diameter, regardless oftheir appearance, they are removed from the locomotive and scrapped.

It has heretofore been the practice to construct locomotive axles andcrank pins from solid forgings. The axles maybe as much as fourteeninches or larger in diameter and seventy inches in length. The crankpins may be as much as twelve inches or more in diameter and twenty-fourinches in length. With such large forgings, the only metal entering intothe structure which isa 'equately worked is that extending inwardly .80I

from the surface to a depth of two orthree inches. The metal of thecenter of the forgings receives inadequate working and ruptures occurduring the forging and tempering processes within the interiors of the 5large bodies of metal. Furthermore, the difficulties of suitablyannealing and tempering such forgings are very great' as it ispractically impossible to heat the interiors to' as high temperatures asthe surfaces. With w an axle as large as thirteen inches in diameter,for instance, it is considered best practice to heat the axle forthirteen hours to bring it to the required temperature for annealing anda corresponding length of time is required for cooling and normalizingit.

It is accordingly apparent that a structure which combines the qualitiesof resiliency, ductility, and wearing properties suitable for theexterior, and tougher, stronger, strain resisting materials for theinterior, the whole being heat treated to a more exact and uniformdegree, is one which would give a much longer, more satisfactory, moredurable service life, and is therefore more desirable.

In accordance with my invention, I attain the above much desiredobjects, by first forging an axle or crank pin from a solid billet ofsteel having qualities suitable for the exterior wearing surface. I thenbore out a considerable amount of the interior portion which can not beso effectively worked by before mentioned suitable for the interior ofthe axle. If the core is eight inches or more in diameter, I preferablybore out its center, removing from two to two and one half inchesdiameter of the center thereof. This central core is then accuratelyalso heat treated and preferably quenched in oil, drawn and cooled inthe furnace in most approved manner. The time of heating and coolingwill be proportionately the same as that for the exteri or shell.

By way of illustration, the following sets forth in tabular form theheat treatment, chemical composition, and physical properties of thematerials which I have found suitable in the construction of locomotiveaxles and crank pins as herein set forth. The data being given for theouter shell and the core respectively. It will be apparent, however,that these details may be varied in wide ranges without departing fromthe scope of my invention.

Outer shell Material Heat treatment Chemical composition Physicalproperties Nickel steel Normalized and drawn. Cooled in the Carbon....20 to 27% Yield point 55, 0005 furnace. Manganese.. .80 to 1.00 Tensilestrength 80, 000:: Phosphorus. maximum 045 Elongation 28% Sulfur maximum045 Reduction of area... 60% Nickel 2. 40 to 2.

All minimum values. Silicon 15 to 25 Gore Material Heat treatmentChemical composition Physical properties Chrome-nickel steel Oilquenched and drawn. Cooled in Carbon 45 to 55% Yield point 110, 000% thefurnace Manganese. 30 to 60 Tensile strength. 130, 0003 Phosphorus.. notover 04 Elongation 18 Sulphur. not over 045 Reduction of area..-- 55%Nickel 1. 5 to 2. 0

All minimum values. Chromium to 1. 25

forging, removing as much as 50 to 60% of the mass of the material. Thecylindrical shell thus formed isthen heat treated in the usual way anddue to its reduced thickness and mass, can be brought to a suitable heatfor annealing more effectively and in a much shorter period of time thancan be done with a solid forging, and cooled down in a correspondinglyshorter time.

For example,'with a thirteen inch outside diameter axle shell bored outto form a two inch thick shell structure it can be brought to a propertemperature for annealing within three hours and held at thattemperature for two hours with a correspondingly rapid cooling actionthrough the critical range for normalization. The resulting shell has afar more homogeneous grain or crystalline structure than is possible toobtain in a solid.

forging thirteen inches in diameter.

I next provide a core for the axle or crank pin, as the case may be,which is made from a steel forging having properties as herein- Afterthe central core is forged,-then, bored if necessary, and heat treatedas hereinbefore set forth, it is turned to tightly fit within the boredexterior or outer shell of the axle or crank pin. It is then fitted intothe outer shell in a manner to form aunitary composite structure, by ahydraulic press or by shrinking in place, by the outer shell coolingfrom its heat treatment with the core insert- 4 ed or by combination ofthese two, or by any suitable means known to the art.

In the drawing hereto annexed and forming a part of this application,

Fig. 1 is a view partially in section and partially in elevation, showinthe locomotive driving wheel assembly 0 my arrangement having theimproved axle and crank pin construction embodied therein; and

Fig. 2 is a cross sectional view taken along the line II-II of Fig. 1.

Referring to the drawing for a better understanding of my invention, Ishow a pair of locomotive driving wheels 10 mounted in a frame 11. Thedriving wheels 10 are mounted upon an axle comprising an outer shell 12and an inner core 13, both constructed as hereinbefore set forth. Theaxle is mount ed in a driving box 14 having the usual bearing 16therein.

Carried by each of the driving wheels 10 is a crank pin comprising alsoan outer shell 17 and an inner core 18, both constructed as hereinbeforeset forth. The outer surface of the crank pin shell 17 is turned toprovide bearing surfaces 19 and 21 for the locomotive rods, not shown.

The outer ends of the pins 18 are provided with portions for engagementwith the usual crank arms in customary fashion. It is also preferable,after forging the inner cores 13 of the axle and 18 of the pin, to borethem out centrally as at 22 and 23 in order to detect flaws intheinterior of the metal and also to facilitate the heat treatmentthereof.

' With axles and crank pins of the sizes described, the amount ofmaterial removed may beas much as two inches diameter or over.

The shell and core of the composite arrangement described each hasapproximately one half the cross sectional area of the complete axle orcrank pin and accordingly about i strength for the composite structureover a similar size solid structure.

It will be apparent that the forging and heat treatment of the smallersections comprising the shell and core of the composite structure may bemore readily handled when tempered and quenched and treated in oil,

such as is practiced by present day metallurgists, as it is wellunderstood that high carbon alloy steels do not as satisfactorily quenchin large as they do in small sections, and in this way effecting animprovement.

It will furthermore be apparent that by the use of my improved compositestructure I provide one comprising an outside part of steel havingproperties that resist heat stresses, chafing and rolling action morereadily and one having a higher ductility. The interior also beingcomprised of a core of steel which is not required to resist the heatstresses of the exterior, but has greatly improved physical propertiesover a heat resisting and disseminating steel when made in the solid, inthe way of greater strength and toughness, the whole resulting in acomposite structure having greater strength and longer life than hasheretofore been possible.

While I have shown my invention in but one form, it will be obvious tothose skilled in the art that it is not so limited, but is susceptibleof various changes and modifications without departing from the spiritthereof, and I desire, therefore, that only such limitations shall beplaced thereupon as are imposed by the prior art or as are specificallyset forth in the appended claims.

What I claim is:

1. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed, boring out theinterior of the member, heat treating the hollow shell thus formed,forging a core to fit the hollowshell, and'forcing the core into thehollow shell to form a composite structure, without further heating theshell.

2. The method of constructing loco-motive axles and crank pins whichconsists in forging solid the member to be constructed, boring out theinterior of the member, heat treating the hollow shell thus formed,forging a core to fit the hollow shell, heat treating the core, andwithout subjecting either of said parts to further heating joining thecore to the hollow shell to form a composite structure.

3. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed. and of amaterial adapted to Withstand bearing friction, boring out the interiorof the member to form a hollow shell, heat treating the hollow shell,forging a core for the shell from relatively tougher material than theshell, and

fitting the core to the shell without further heating of the shell, in amanner to obtain a substantially solid composite structure.

4. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed and of a materialadapted to withstand bearing friction, boring out the interior of themember to form a hollow shell, heat treating the hollow shell, forging acore for the shell from relatively tougher material than the shell, heattreating the core, and without further heating the core or the shellfitting the core to the shell in a manner to obtain a substantiallysolid composite structure.

5. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed and'of a materialadapted to withstand bearing friction, boring out the interior of themember to form a hollow shell, heat treating the hollow shell, forging acore for the shell from relatively tougher material than the shell, heattreating the core, and without further heating the core or the shell,press fitting the core to the shell to obtain a substantially solidcomposite structure'.

6. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed, boring out theinterior of the member centrally thereof to remove substantially 50% ofthe material thereof, heat treating the resulting cylinder, forging acore for the heat treated 5 cylinder, and without further heating thecylinder, tightly fitting the core into said cylinder.

7. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed, boring out theinterior of the member centrally to remove up to 60% of the materialthereof, heat treating the resulting cylinder, forging a core for theheat treated cylinder, heat treating the core, and without further heattreating the core or the cylinder tightly fitting the core into saidcylinder.

8. The method of constructing locomotive axles and crank pins whichconsists in forging solid the member to be constructed and of a materialadapted to withstand bearing friction, boring out the interior of themember centrally thereof to remove material ineffectively worked byforging, heat treating the resulting cylinder, forging a core for thecylinder of a relatively tougher material than the cylinder, boring outthe core centrally thereof, heat treating the core, and pressing thecore into the cylinder to form a composite structure.

9. In a device of the characterdescribed, an outer heat treated shell ofrelatively hard, ductile resilient steel, and an inner central corefirmly mechanically united to the outer shelland comprising separatelyheat treated steel relatively tougher, stronger and harder than theouter shell.

10. In a device of the character described, an outer heat treated shellof relatively hard, ductile resilient steel, and an inner central corefirmly united to the outer shell and comprising separately heat treatedsteel relatively tougher, stronger and harder than the outer shell, saidinner core comprising approximately 50% of the total mass of the device.

11. In a device of the character described, an exterior shell of heattreated steel of relatively low carbon content and relatively lowtensile strength, said shell comprising as much as 50% of the mass ofthe device and a central core rigidly joined to the exterior shell andof separately heat treated steel of a higher carbon content and highertensile strength than the exterior shell.

12. In a locomotive axle, an exterior cylindrical shell of heat treatedmaterial having relatively high ductility and relatively high frictionalresistance properties, and a separately heat treated cylindrical corerigidly joined to the outer shell and having relatively greater tensilestrength and higher yield point than the exterior shell.

13. In a locomotive crank pin, an exterior C3 cylindrical shell of heattreated material having relatively high ductility and relative.- ly highfrictional resistance properties, and a. separately heat treatedcylindrical core rigidly joined to the outer shell having relativelygreater tensile strength and higher yield point than the exterior shell.

14. A locomotive axle comprising a heat treated steel outer shellcomprisin not less than sixty percent of the mass of the axle and'havinga tensile strength of not less than 80,000 pounds and a yield point ofnot less than 55,000 pounds; and a central separately heat treated steelcore rigidly joined to the outer shell and having a tensile strength ofnot less than 130,000 pounds and a yield point of not less than 110,000pounds.

15. A locomotive axle comprising a heat treated steel outer shellcomprising not less than sixty percent of the mass of the axle andhaving a tensile strength of not less than 80,000 pounds and a yieldpoint of not less than 55,000 pounds; and a central separately heattreated steel core rigidly joined to the outer shell and having atensile strength of not less than 130,000 pounds and 'a yield point ofnot less than 110,000 pounds, said central core being bored for heattreatment and having not more than percent of its material removed.

In testimony whereof I aflix my si nature.

CHARLES J. SCUDIDER.

